A decrease in the reserve requirement causes the size of the money multiplier to multiple choice increase, the amount of excess reserves in the banking system to rise, and the money supply to decrease. decrease, the amount of excess reserves in the banking system to rise, and the money supply to increase. increase, the amount of excess reserves in the banking system to rise, and the money supply to increase decrease, the amount of excess reserves in the banking system to rise, and the money supply to decrease